Xx ove oven-thermometer



"(No Model.)

1). e. COOPER. OVEN THERMOMETER.

Patented Oct. 20,1885.

N. PETERS, meum gnwer. Wmin mn. u (g ll'rrnn slam PATENT FFlQE DAVID G. COOPER, OF DOVER, NEW HAMPSHIRE.

OVEN-TH ERMOMETER.

FJPECJIFICATION forming part of Letters Patent No. 328,878, dated October 20, 1885.

Application filed March 28, 1885. Serial No. 160,521. (No model.)

To all whom it may concern.-

Be it known that I, DAVID G. COOPER, a citizen of the United States, residing at Dover, in the county of Strafford and State of New Hampshire, have invented certain new and useful Improvements in Oven-Thermometers; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

This invention relates to devices for measuring and indicating the heat of an oven, kiln, or similar heating surface or chamber; and the invention consists of a casing that incloses a system of expansible metallic bars, multiplying-levers, connecting rod or bar, and a pinion and segment-gear, in combination with a dialcase and an index-finger, the latter being attached to the pinion-shaft; and it further consists in certain details of construction, as hereinafter specified.

In the annexed drawings, illustrating the invention Figure 1 is a plan view of my improved pyrometer mechanism. Fig. 2 is aside view of the pyrometer-casing in position, with the dial-case and a portion of the stove and oven in section. Fig. 8 is a face view of the dial and index-finger.

Like letters of reference refer to like parts in the several views.

Arepresents the thermometer-casing,which is provided with a movable cover, B,with1ugs a a for supporting said cover, and with a'barrel-bearing, b, for a screw, by which the cover is secured. This casing may be supported in any convenient manner within an oven, (a portion of which is shown in section at 0,) and may have on its outer sidea hub, 0, and lugs d d, that bear against the side of said oven.

Within the casing A,which maybe made of cast-iron, are guides e e, for the expansible inetallic bars D D, that are preferably made of brass, or of some metal that readily expands with any increase of temperature, but in a different ratio from the expansion of the casing. Arranged at right angles with the expansible bars D D are pivoted the multiplying-levers E E, that are preferably made of cast-iron, though other material may be used.

Through one corner of the casing Ais inserted an adjusting-screw, F, the inner end of which bears against the end of one of the expansible bars. By turning this screw the bars D D and levers E E are moved sufficiently to adjust the index-finger M as may be required.

To the end of the multiplying-lever E is pivoted a connecting rod or bar, G, the opposite end of which is attached to the pivoted arm of a segmentgear, H, that meshes with a pinion, K, on the shaft L of an index-finger, M, which is exposed to view on the face of a dial exterior to the stove.

The shaft L, that supports the pinion K and index-finger M, may be of any required length, and is preferably inclosed in a tube, N, that extends across the space between the oven-lining Oand the stove-body P, as shown in Fig. 2. This tube may support on one end the hub c of the pyrometer-oasing A, and at its other end the hub f of the dial-back Q, as shown; or said parts may be supported in any convenient manner. The back of the dial may be recessed for a nut, g, by which it is attached to the threaded end of the tube.

To the dial-back Q is attached a dial-face, R, that may be graduated similar to a clockdial, and be provided with marks indicating degrees of heat and the temperatures at which various articles of food should be cooked. A transparent cover, S, is attached over the dialface and index-finger by means of a metallic rim or band, T, as shown in Fig. 2. It will be seen that the expansion or lengthening of the bars D D by heat will cause them to bear against the adjacent ends of the levers E E, which are thus actuated, the movement produced by the expansion of the bar D being multiplied by the action of the lever Eon the bar D, which, together with the expansion of the latter bar, actuates the lever E, and through it the connecting rod or bar G, segment-gear H, and pinion K, thereby imparting a rotary motion to the shaft L and attached index-finger. This movement continues with each increase of temperature in the oven, the degree of which is indicated by the index-finger M on the face of the dial. As the temperature in the oven becomes reduced, the contraction of the ther mometer mechanism is supplemented by the action of a castiron spring, U, that is so arranged that one end will bear against a shoulder, h, on the arm H of the segment-gear H, the pinion K and the index-finger being thus gradually moved backward. The spring U is preferably made of cast-iron, the elasticity of such metal not being readily affected by high temperatures. The tension of the spring U is regulated by means of a screw, 70, that engages a nut, m, fixed to the interior of the casing near a shouldered or notched lug, a, that supports one end of the spring. Instead of the spring U,the segment-gear might be returned by means of a weight connected to an arm of the gear-hub, as shown by dotted lines in Fig. 1. The end of the lever E may be provided with a series of pivot-holes for the attachment of the connecting-bar G, as shown, thus providing a means of adjusting said bar, as required. The shaft L and the pivot of the segment-gear H may have bearings directly in the oven-lining, or in a plate or plates, 19, attached thereto.

For lubricating the several bearings and points of movement I prefer to use graphite or plumbago, which will produce good results at all temperatures to which the devices will be ordinarily exposed.

The simplicity of arrangement and ease of adjustment in the various parts of the mech anism are such as to render the operation of the devices reliable in ascertaining the temperature of a heated oven.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a thermometer, the combination,with the expansible bars D D and levers E E, of the segment-gear H, connecting-bar G, pinion K, shaft L, index-finger M, and a dial, R, substantially as described.

- 2. The combination, with the expansible bars D D, levers E E, connecting-bars G, segmental gear H, having an arm, H, provided with shoulder h, the pinion K, shaft L, and index-finger M, of the cast-iron spring U, having an adjusting-screw, k, substantially as described.

3. The combination of the casing A, provided internally with guides e e, the expansible bars D D, supported in said guides, the pivoted levers E E, the screw F, for adjusting said bars and levers, the pivoted segmentgear H H, connectingbar G, adjustable spring U, shaft L, the pinion K, and indexfinger M, mounted on said shaft, and a dial, R, graduated to indicate the temperatures at which various articles of food should be cooked, substantially as described.

In testimony whereof I afiix my signature in presence of two witnesses.

DAVID G. COOPER.

\Vitnesses:

EUGENE SMART,

M. P. FARNHAM. 

